Variable light signal delay apparatus, and variable light signal delay system using the same

Abstract

A variable light signal delay apparatus includes a first delay optical fiber, a second delay optical fiber having a length different from the first delay optical fiber, and an optical switch having two input ports, two output ports, and paths, through which a light signal propagates, provided between the first delay optical fiber and the second delay optical fiber, in which a light signal input from at least one of the input ports propagated through either the first delay optical fiber or the second delay optical fiber or through neither the first delay optical fiber nor the second delay optical fiber to be output from a desired first output port.

1. A variable light signal delay apparatus, comprising:
 a first delay optical fiber; 
 a second delay optical fiber having a length different from the first delay optical fiber; and 
 a first optical switch having two first input ports, two first output ports, and paths, through which a light signal propagates, provided between the first delay optical fiber and the second delay optical fiber, in which a light signal input from at least one of the first input ports is propagated through either the first delay optical fiber or the second delay optical fiber or through neither the first delay optical fiber nor the second delay optical fiber to be output from a desired first output port; 
 wherein the first optical switch comprises four switching portions monolithically formed on one substrate, and the four switching portions are coupled to each other through an optical waveguide. 
 
   
   
     2. The variable light signal delay apparatus according to  claim 1 , wherein the first optical switch switches an output-side path of a light signal to one of two ways, and
 the four switching portions are: 
 an input-side switching portion to which light signal is input from at least one of the first input ports, 
 an output-side switching portion which switches the output-side path to output a light signal from a desired output port, 
 a first switching portion which forms a loop with the first delay optical fiber, in which a light signal output from one output path of the input-side switching portion is propagated through the first delay optical fiber or not through the first delay optical fiber to output to the output-side switching portion, and 
 a second switching portion which forms a loop with the second delay optical fiber, in which a light signal output from another output path of the input-side switching portion is propagated through the second delay optical fiber or not through the second delay optical fiber to output to the output-side switching portion. 
 
   
   
     3. A variable light signal delay system, comprising:
 a plurality of the variable light signal delay apparatus according to  claim 1 , which are provided in parallel; 
 a second optical switch having two second input ports, in which a light signal input from at least one of the second input ports is output to a desired variable light signal delay apparatus through a path to be switched by the second optical switch; and 
 a third optical switch having two second output ports, in which a light signal input from the desired variable light signal delay apparatus is output from a desired second output port through a path to be switched by the third optical switch; 
 wherein first delay optical fiber and the second delay optical fiber provided in the plurality of variable light signal delay apparatuses have different lengths. 
 
   
   
     4. The variable light signal delay system according to  claim 3 , further comprising:
 a plurality of optical fibers which connect each of the variable light signal delay apparatuses and the third optical switch, and have a different length respectively. 
 
   
   
     5. A variable light signal delay system, comprising:
 a plurality of the variable light signal delay apparatus according to  claim 1 , which are provided in parallel; 
 a second optical switch having two second input ports, in which a light signal input from at least one of the second input ports is output to a desired variable light signal delay apparatus through a path to be switched by the second optical switch; 
 a third optical switch having two second output ports, in which a light signal input from the desired variable light signal delay apparatus is output from a desired second output port through a path to be switched by the third optical switch; and 
 a plurality of optical fibers which connect each of the variable light signal delay apparatuses and the third optical switch, and have a different length respectively. 
 
   
   
     6. The variable light signal delay system according to  claim 3 , wherein the first optical delay fiber in each of the plurality of light signal delay apparatuses is of an identical length. 
   
   
     7. The variable light signal delay system according to  claim 6 , wherein the second optical delay fiber in each of the plurality of the variable light signal delay apparatus is of an identical length. 
   
   
     8. The variable light signal delay system according to  claim 5 , wherein the first optical delay fiber in each of the plurality of the variable light signal delay apparatus is of an identical length. 
   
   
     9. The variable light signal delay system according to  claim 8 , wherein the second optical delay fiber in each of the plurality of the variable light signal delay apparatus is of an identical length. 
   
   
     10. The variable light signal delay system according to  claim 3 , wherein a third optical delay optical fiber is disposed between one of the plurality of the variable light signal delay apparatus and the third optical switch. 
   
   
     11. The variable light signal delay system according to  claim 5 , wherein a third optical delay optical fiber is disposed between one of the plurality of the variable light signal delay apparatus and the third optical switch. 
   
   
     12. The variable light signal delay apparatus according to  claim 1 , wherein the paths comprise:
 a path which propagates the light signal through the first delay optical fiber; 
 a path which propagates the light signal through the second delay optical fiber; and 
 a path which propagates the light signal straight through the first optical switch no delay. 
 
   
   
     13. The variable light signal delay apparatus according to  claim 2 , wherein each of the switching portions allow the light signal to continue through the switching portion if the switching portion is turned off, and do not allow the light signal to pass if the switching portion is turned on. 
   
   
     14. The variable light signal delay apparatus according to  claim 13 , wherein the light signal passes straight through the first optical switch when the first switching portion is turned on. 
   
   
     15. The variable light signal delay apparatus according to  claim 13 , wherein the light signal passes straight through the second switching portion when the second switching portion is turned on. 
   
   
     16. The variable light signal delay apparatus according to  claim 3 , wherein each of the first delay optical fiber and the second delay optical fiber provided in each of the plurality of variable light signal delay apparatuses has a different length.